Electronic musical instrument producing percussion signals by additive mixing of component signals

ABSTRACT

An electronic musical instrument for simulating percussion sounds comprises a touch-responsive keyboard section for generating a voltage whose level varies in accordance with the magnitude of force with which the key is depressed to give forth percussion sounds, a low frequency oscillator having a relatively long period of oscillation activated by signal from said section and a similarly activated high frequency oscillator having a relatively short period of oscillation, wherein the levels of signals from both of the oscillators are respectively controlled according to the magnitude of voltage derived from said touchresponsive keyboard section in such a manner that the voltage level of the high frequency oscillator is controlled to a greater extent than that of the low frequency oscillator, and there are mixed a controlled signal component from said high frequency oscillator and a signal component from said low frequency oscillator so as to generate percussion sounds more truthfully simulating those of a natural percussion instrument.

United States Patent l l 1 1 I I PRODUCING PERCUSSION SIGNALS BY ADDITIVE MIXING OF COMPONENT SIGNALS 7 Claims, 8 Drawing Figs.

(52] U.S.CI 84/].26, 84/1.1,84/1.27, 84/122 [51] Int. Cl G10h 5/08, GlOh 1/02 [50] Field of Search 84/].01, 1.09,1.1,1.12,1.13,1.15,1.21,1.22,1.24,1.26, 1.27

[5 6] References Cited UNITED STATES PATENTS 3,003,383 10/1961 Williams 84/1.26 3,235,650 2/1966 Cutler etal. 84/126 3,291,886 12/1966 Tinker 84/1.01 3,328,506 6/1967 Park 84/1.24 3,465,087 9/1969 Brand et a1. 84/126 3,497,605 2/1970 Hebeisen et a1. 84/1 .1 3 FOREIGN PATENTS 1,162,449 8/1969 Great Britain 84/126 1,164,442 9/1969 Great Britain 84/126 Primary ExaminerMilton O. I-Iirshfield Assistant ExaminerStan1ey .l Witkowski Atl0rneylrving M. Weiner ABSTRACT: An electronic musical instrument for simulating percussion sounds comprises a touch-responsive keyboard section for generating a voltage whose level varies in accordance with the magnitude of force with which the key is depressed to giveforth percussion sounds, a low frequency oscillator having a relatively long period of oscillation activated by signal from said section and a similarly activated high frequency oscillator having a relatively short period of oscillation, wherein the levels of signals from both of the oscillators are respectively controlled according to the magnitude of voltage derived from said touch-responsive keyboard section in such a manner that the voltage level of the high frequency oscillator is controlled to a greater extent than that of the low frequency oscillator, and there are mixed a controlled signal component from said high frequency oscillator and a signal component from said low frequency oscillator so as to generate percussion sounds more truthfully simulating those of a natural percussion instrument.

'FORMING ,CIRCUIT w f SECOND WAVE SECOND OSCILLATOR 'AMPLI Fl ER FIG.

FIG.

FIG.

- PATENTEU JUN H971 SHEET 2 OF 2 9 KEY DEPRESSED KEY RELEASED IN Vlz'N'l'OR. TAKE HI ADACHI ATTORNEY 1 ELECTRONIC I'viusIcaL INSTRUME T PRODUCING PERCUSSION sI cNALs rv ADDITIVE MIXING or COMPONENT SIGNALS BACKGROUND OF THE INVENTION The present invention relates to an electronic musical instrument for simulating percussion sounds.

The moment there is strongly beaten a natural percussion instrument, it generally gives forth a prominent attack sound mainly consisting of a component of relatively high frequency. However, said attack sound decays relatively quickly and, after a certain length of time, is'turned into adecay'in'g sound primarily formed of a component of i'elatively low frequency which decays rather slowly and trails long. Conversely where said instrument is gently tapped, the total volume becoming soft, the attack sound'becomes less prominent and a decaying sound predominates. Namely, with a natural percussion instrument, not only the volume, but also the color of'tones vary with the magnitude of force with which it is beaten.

The prior art electronic musical instrument for simulating percussion sounds comprises a touch-responsive keyboard section for generating a voltage whose level varies in ac cordance with the magnitude of force with which a percussion key is depressed and an oscillator which has a level of oscillating voltage (tone signal amplitude) corresponding to the voltage supplied from the touch-responsive keyboard section and displays decayingoscillations, thereby simulating percussion sounds with .outputs from said oscillator. With such conventional electronic musical instrument, therefore, the varying magnitude of force with which the key is depressed only leads to change in the volume of tones and not in the color thereof, so that the performance of said prior art instrument widely dcparts from that of a natural percussion instrument.

SUMMARY OF THE INVENTION lowing not only the volume but also the color of tones to vary with the magnitude'of force with which the key is depressed, thereby generating percussion sounds bearing more truthful .resemblance to those derived from a natural percussion instrument.

According tothe invention, there is provided an electronic musical instrument comprising means for generating a voltage whose level varies in accordance with the magnitude of force with which the key'is depressed, a first waveforming device for shaping the waveform of voltage supplied by said voltage generator into that which has a slow attack and a long decay, a second waveforming device for shaping the waveform of said voltage into that which has a fast attack' and a short decay, a first oscillator for generating signal of relatively low frequency which is modulated in amplitude by output signal from said first waveforming device, a second oscillator for generating signal of relatively'high frequency which is modulated in amplitude by output signal from said second waveforming device, means for further'controlling the level of output signal from said second oscillator according to'the level of voltage derived from said voltage generator, means for jointly amplifying output signals from said first and second oscillators and a loud speaker derived by output signals from said amplifying means.

According -to the electronic musical instrument of the present invention, there are mixed attack sound mainly consisting of a component of relatively high frequency which has a relatively short period of rising and decaying, and decaying sound essentially formed of a component of relatively low frequency whichh'as a relatively long period of rising and decaying, both sounds are so controlled as to make'voltage levels responsive to the magnitude of a force with which the key is depressed, and only said'attack sound is further controlled according to the magnitude of force with which the key is depressed, so that said instrument conducts a percussion performance wherein the attack and decaying sounds are 'mixed in a varying ratio, thereby controlling not only the volume, but also the color of tones at the same time.

BRIEF EXPLANATION OF THE DRAWINGS The invention will be more fully understood from the following description taken with reference to the accompanying drawings, in which:

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, output voltage from a touch-responsive keyboard section 1 capable of generating a DC voltage whose level varies in accordance with the magnitude of force with which the key is depressed, is supplied to first and second waveforming circuits 2 and 3 and DC amplifier 4.

The first and second waveforming circuits 2 and 3 shape output voltage from the touch-responsive keyboard section 1 into driving signals which have predetermined period of rising and decaying as percussion envelopes. Output voltages from the waveforming circuits 2 and 3 whose waveforms are shaped to be driving signals thereby are supplied to first and second sinc wave oscillators 5 and 6. The frequencies of the oscillators 5 and 6 are preferably so set as not to be harmonically related as described below. The frequency of the latter 6 is chosen to be higher than that of the former 5. Output voltage from the second waveforming circuit 3 has a shorter period of rising (fast attack) and decaying (short decay) than that from said first waveforming circuit 2. Output signal from the first waveforming circuit 2 is supplied, as described below, to the first oscillator 5 to activate it and modulate, in response to the depression force of the key, the amplitude of sine wave signal from the first oscillator 5 substantially consisting of a component of relatively low frequency. On the other hand, output signal from the second waveforming circuit 3 is supplied, as described below, to the second oscillator 6 to activate it and modulate, in response to the depression force of the key, the amplitude of sine wave signal from the second oscillator 6 substantially formed of a component of relatively high frequency, and thereafter conducted to an amplitude modifier 7, which is impressed at this moment with a DC voltage from the touchresponsive keyboard section 1 through the DC amplifier 4. From the amplitude modifier 7, therefore, is derived a signal which has been obtained by further controlling the level of the aforesaid amplitude modulated signal from the second oscillator 6 according to the magnitude of DC voltage from the DC amplifier 4. Signals from the first oscillator 5 and amplitude modifier 7 are mixed and supplied through a common amplifier 8 to a loud speaker 9 to drive it, thereby simulating desired percussion sounds.

There will now be described by reference to FIG. 2 the respective sections of the block diagram of FIG. 1. The touchresponsive keyboard section 1 has a magnet 101 disposed below a percussion key of a keyboard-type electronic musical instrument, for example, an electronic organ. There is further provided a coil 10 2 at a position at which there is cut off the flux from the magnet 101 which is moved along as a result of the depression of the percussion key 100. One end of the coil 102 is grounded and the other end is connected through a capacitor 103 to the base 105 of a first NPN type transistor 104. The emitter 106 of the transistor 104 is grounded through a resistor 107, and its collector 108 is connected through a resistor 109 to the terminal 121 of a B source. Further, the base 105 of the transistor 104 is connected to the junction of resistors 110 and 111 connected in series between the terminal 121 and ground, so as to be impressed with a prescribed DC bias voltage. The collector 108 of the transistor 104 is connected to the base 113 of a second NPN type transistor 112. Its collector 114 is connected to the terminal 121, and its emitter 115 is grounded through a resistor 116, and also connected to the anode of a diode 117 for rectifying signal amplified by the transistors 104 and 112. The

cathode of the diode 117 is grounded through a capacitor 118. Parallel to said capacitor 118 is connected a series circuit consisting of a resistor 119 and a normally closed contact switch 120 which is mode open while the key is depressed.

When the key 100 of the touch-responsive keyboard section 1 is depressed there is generated in the coil 102 a pulse voltage whose level varies in accordance with the magnitude of force with which the key is depressed. The pulse voltage is amplified by said transistors 104 and 112. The amplified pulse voltage derived from the emitter 115 of the transistor 112 is rectified by the diode 117 to charge the capacitor 118 to a corresponding voltage. Since the normally closed contact switch 120 is left open while the key is depressed, the capacitor 118 retains the charged voltage. When the key is released, the normally closed contact switch 120 is closed to allow the capacitor 118 to be discharged through the resistor 119, When the key is depressed with various magnitudes of force, there are generated in-the coil 102 voltages whose levels are responsive thereto, causing the capacitor 118 to be charged to corresponding different levels of voltage. In this case, the more strongly the key is depressed, the more increased the voltage of the capacitor 118. Thus the voltage at the junction between said diode 117 and the capacitor 118, namely, the output voltage from the touch-responsive keyboard section 1 will assume such a waveform as shown in FIG. 3A, wherein the uppermost solid line represents that level of voltage which is generated when the key is strongly depressed, the middle broken line the level of said voltage appearing when said key depression is made with a medium force and the lowermost broken line the level of said voltage occurring when the key is softly depressed. Output voltage from the keyboard section 1 is supplied to the first and second waveforming circuits 2 and 3 and DC amplifier 4. Input voltage to the first wave forming circuit 2 is conducted to the gate 201 of an insulated gate field effect transistor 200. The drain 202 of said transistor 200 is con nected to the terminal 228 of a +8 source and its source 203 is grounded through resistor 204. The source 203 of theinsulated gate field effect transistor 200 is connected to the base 206 of an NPN transistor 205. Its collector 207 is connected to the terminal 228 through a resistor 208 and its emitter 209 is grounded through a resistor 210. The collector 207 of a transistor 205 is connected to the base 212 of a PNP type transistor 211, and its emitter 213 is connected to the terminal 228 through a resistor 214 and its collector 215 is grounded through a resistor 216. The collector 215 ofa transistor 211 is connected to the base 218 of an NPN type transistor 217, its collector 219 is connected to the terminal 228 and its emitter 220 is grounded through a resistor 221. The emitter 220 ofthe transistor 217 is connected to one end of a capacitor 222 and the other end of the capacitor 222 is connected to the cathode of a diode 223 and the anode of the diode 223 is grounded. The junction of the capacitor 222 and the diode 223 is connected to the anode of a diode 224. The cathode of the diode 224 is connected to one end of a capacitor 226 through a resistor 225, and the other end of the capacitor 226 is grounded. Parallel to the capacitor 226 is connected a resistor 227. Output signal from the first waveforming circuit 2 is derived from the junction voltage from the touch-responsive keyboard section 1 is amplified by the transistors 200, 205, 211 and 217 of the waveforming circuit 2. Amplified output is derived from the emitter 220 of the transistor 217, and supplied to the resistor 225 and the capacitor 226 through the capacitor 222 and the diode 224 so as to be integrated.

The first waveforming circuit 2 converts the voltage of the touch-responsive keyboard section 1 into a driving signal which has a relatively long period of rising and decaying, so that the integrating circuit consisting of the resistor 225 and the capacitor 226 will have a relatively large time constant, resulting in a slow attack period. Since the time constant of the discharge circuit of the capacitor 226 also increases, there is obtained a long decaying period by connecting the resistor 227 having a large value parallel to the capacitor 226. ln this case, it is preferred to set the rising period at about 30 msec.

(milliseconds) and the decaying period at about 500 msec. Output voltage from the first waveforming circuit derived from the junction of the resistor 225 and the capacitor 226 assumes such a waveform as shown in FIG. 35 wherein the uppermost solid line represents that level of voltage which is generated when the key is strongly depressed, the middle broken line the level of said voltage appearing when said key depression is made with a medium force and the lowermost broken line the level of said voltage occurring when the key is softly depressed.

The first low frequency oscillator 5 is provided with'an NPN type transistor 500 and there is connected a resistor 503 between the collector 501 and the base 502 of the transistor 500. The base 502 is connected through a capacitor 504 to one end of a tank circuit 507 consisting of a coil 505 and a capacitor 506 arranged in parallel so as to define the frequency of oscillation. The other end of the tank circuit 507 is connected through a resistor 509 tothe intermediate tap of the coil 505. The collector 501 of the transistor 500 is connected to thejunction of the resistor 225 and the capacitor 226 of the first waveforming circuit 2. Thus, the oscillator 5 is activated by output voltage from the first waveforming circuit 2 and maintains its oscillating condition only while it is supplied with the output voltage. The level of output voltage from the oscillator 5 varies with that of the output voltage from the first waveforming circuit 2 to assume a wave form modulated in amplitude. Output from the oscillator Sis drawn out through a coupling capacitor 510 at the junction of the capacitor 504 and the tank circuit 507. The output is supplied through a mixing resistor 511 to an amplifier 8 in the waveform shown in FIG. 3D. Oscillated sine wave signal of relatively low frequency is modulated in amplitude by output signal from the first waveforming circuit 2.

In the foregoing embodiment, the first oscillator 5 consists of an externally excited type activated by output signal from the first waveforming circuit 2. However, even where the oscillator is of a normally oscillating type and output signal therefrom is gated by output voltage from the first waveforming circuit 2, there will be obtained the same result.

The second waveforming circuit 3 and a circuit associated with the second high frequency oscillator 6 are respectively of the same arrangement as the first waveforming circuit 2 and a circuit associated with the first low frequency oscillator 5, so that description thereof is omitted. With the second waveforming circuit 3, however, the integrating circuit consisting of a resistor and a capacitor corresponding to the resistor 225 and the capacitor 226 of the first waveforming circuit 2 has a smaller time constant than that of the first waveforming circuit 2 so as to obtain a short period ofleading (fast attack), and further the resistor of the second waveforming circuit 3 corresponding to the resistor 227 of the first waveforming circuit 2 is reduced in value so as to obtain a short decaying period (short decay). For the purpose of the present invention, the rising period is preferably set at about 5 msec. and the decaying period at about 50 msec. in the second waveforming circuit 3. Also the inductance of the coil of the second oscillator 6 corresponding to the coil 505 of the first oscillator 5 and/or the capacitance of the capacitor of the second oscillator 6 corresponding to the capacitor 506 of the tank circuit of the first oscillator 5 is reduced so as to carry out oscillation with a higher frequency than is performed by the first oscillator 5.

Outputs from the second waveforming circuit 3 and the second oscillator 6 have waveforms shown in FIGS. 3C and 3E respectively. In FIG. 3C, the uppermost solid line represents that level of voltage which is generated when the key is strongly depressed, the middle broken line the level of said voltage appearing when said key depression is made with a medium force and the lowermost broken line the level of said voltage occurring when the key is softly depressed. As apparent from these waveforms, sine wave signal of relatively high frequency from the second oscillator 6 is modulated in amplitude by output signal from the second waveforming circuit 3. Accordingly, the levels of amplitude modulated signals from the first and the second oscillators 5 and 6 are determined in accordance with the magnitude of voltage supplied from said touch-responsive keyboard section 1.

According to an embodiment of the present invention, the frequencies of the first and the second oscillators are so chosen as not to be harmonically related. For example, where the conga out of percussion instruments is to be simulated, it is preferred that the low frequency be set at about 180 Hz. and high frequency at-about 330 Hz.

And in case of the bongo, the low and high frequencies are preferably set at about 320 and about 800 Hz. respectively,

and in case of the claves at about 1,900 and 4,000 Hz. respectively.

The amplitude modifier 7 is provided with an insulated gate field effect transistor 700 as a variable resistance device. Between a source 702 and a drain 703 of the field effect transistor 700 there is disposed, if necessary, a semistationary resistor 701 so as properly to define the interior resistance of the transistor 700. The source 702 and the drain 703 of the transistor 700 are grounded through resistors 704 and 705 respectively. Output signal from the second oscillator 6 is sup plied to the source 702 of said transistor 700. The amplitude modifier 7 further controls the level of amplitude modulated signal from the second oscillator 6 having a waveform shown in FIG. 3E according to the magnitude of DC voltage supplied through the DC amplifier 4 from the touch-responsive keyboard section 1. Output from the modifier 7 is derived from the junction of the drain 703 of the field effect transistor 700 and the resistor 705, and supplied to the amplifier 8 through a capacitor 707 and a mixing resistor 708. Outputs from the first and the second oscillators 5 and 6 are combined, the composite signal assuming a waveform shown in FIG. 3F.

The DC amplifier 4 is of the same arrangement as the amplifier in the first wave forming circuit 2 formed of the transistors 200, 205, 21 land 217, so that description thereof is omitted. Output from the DC amplifier 4 is derived from the emitter of a transistor corresponding to the last transistor 217 of the first waveforming circuit 2, and supplied through a resistor 410 to the gate 806 ofa transistor 700 involved in the amplitude modifier 7. Thus the resistance across the source and the drain of the transistor 700 is controlled according to the magnitude of output voltage from the DC amplifier 4, thereby further controlling the level of output signal from the second oscillator 6.

As mentioned above, the present invention controls, according to the magnitude of a force depressing the key, the level of the decaying sound and the attack sound in the first place, and further the level of attack sound substantially consisting of a high frequency component having a short period of rising and decaying which is involved in the mixed input signals supplied to the amplifier 8 connected to the loud speaker 9, thereby carrying out a percussion performance more truthfully resembling that of a natural percussion instrument. The more forcefully depressed the key, the more elevated at a greater rate the level of a high frequency component supplied to the amplifier 8 and in consequence the more prominent the attack effect of percussion sounds. Though, in this case, the level of the decaying sound consisting of a low frequency component having a long period of rising and decaying also increases, there prominently appears only attack sound consisting of a high frequency component as the decaying sound is controlled in amplitude at a smaller rate, thus obtaining distinct percussion tones. Where the key is gently tapped, the level of a high frequency component supplied to said amplifier is appreciably more reduced than when the key is strongly depressed, and instead there predominates decaying sound consisting ofa low frequency component, thus producing percussive tones which sound soft as a whole.

We claim:

1. An electronic musical instrument for simulating percussion sounds which comprises means for generating a voltage whose level varies in accordance with a magnitude of force with which a key is depressed, a first waveforming device for shaping output voltage from said voltage-generating means into that whose waveform has a long period of rising and decaying, a second waveforming device for shaping said output voltage into that whose waveform has a short period of rising and decaying, a first oscillator for generating signal of relatively low frequency modulated in amplitude by output signal from said first waveforming device, a second oscillator for generating signal of relatively high frequency modulated in amplitude by output signal from said second waveforming device, means for further controlling the level of output from said second oscillator modulated in amplitude according to the level of voltage supplied by said voltage-generating means, means for jointly amplifying level-controlled output from said second oscillator and output from said first oscillator, and a loud speaker derived by output from said amplifying means.

2. The instrument according to claim 1 wherein the frequencies of said first and second oscillators are so chosen as not to be harmonically related.

3. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about Hz. and the high frequency of said second oscillator at about 330 Hz.

4. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about 320 Hz. and the high frequency of said second oscillator at about 800 Hz.

5. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about 1,900 Hz. and the high frequency of said second oscillator at about 4,000 Hz.

6. The instrument according to claim 1 wherein said first and second oscillators are activated by output from said first and second waveforming devices.

7. The instrument according to claim 1 wherein output voltage from said first waveforming device has a rising period of about 30 msec. and a decaying period of about 500 msec., and output voltage from said second waveforming device has a rising period of about 5 msec. and a decaying period of about 50 msec. 

1. An electronic musical instrument for simulating percussion sounds which comprises means for generating a voltage whose level varies in accordance with a magnitude of force with which a key is depressed, a first waveforming device for shaping output voltage from said voltage-generating means into that whose waveform has a long period of rising and decaying, a second waveforming device for shaping said output voltage into that whose waveform has a short period of rising and decaying, a first oscillator for generating signal of relatively low frequency modulated in amplitude by output signal from said first waveforming device, a second oscillator for generating signal of relatively high frequency modulated in amplitude by output signal from said second waveforming device, means for further controlling the level of output from said second oscillator modulated in amplitude according to the level of voltage supplied by said voltage-generating means, means for jointly amplifying leveL-controlled output from said second oscillator and output from said first oscillator, and a loud speaker derived by output from said amplifying means.
 2. The instrument according to claim 1 wherein the frequencies of said first and second oscillators are so chosen as not to be harmonically related.
 3. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about 180 Hz. and the high frequency of said second oscillator at about 330 Hz.
 4. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about 320 Hz. and the high frequency of said second oscillator at about 800 Hz.
 5. The instrument according to claim 2 wherein the low frequency of said first oscillator is set at about 1,900 Hz. and the high frequency of said second oscillator at about 4,000 Hz.
 6. The instrument according to claim 1 wherein said first and second oscillators are activated by output from said first and second waveforming devices.
 7. The instrument according to claim 1 wherein output voltage from said first waveforming device has a rising period of about 30 msec. and a decaying period of about 500 msec., and output voltage from said second waveforming device has a rising period of about 5 msec. and a decaying period of about 50 msec. 